Updated: September 20, 1999
Hello,
Please find attached to this message a new JOP proposal (or an update of
JOP58) involving
CDS, SUMER and MDI, which could be run during the next MEDOC campaign
(4th/17th October).
I hope this proposal is complete. Let me know if it was not the case.
Please, let me also know what steps we should now take?
Thanks,
Frederic Baudin (baudin@ias.fr)
JOP (SOHO): Observational Proposal submission (e-mail version)
--------------------------------------------------------------
"Search of propagating waves over the chromospheric network"
F. Baudin(1), K. Bocchialini (1), P. Gallagher (2),
P. Gouttebroze (1), S. Koutchmy (3), P. Lemaire(1)
(1) Institut d'Astrophysique Spatiale, Bat. 121, Universite Paris XI/CNRS,
91405 Orsay, France
(2) Departement of Pure and pplied Physics, Queen's University of Belfast,
Ireland
(3) Institut d'Astrophysique de Paris/CNRS, 98 bis Bd Arago, 75014 Paris,
France
A) Scientific background
---------------------
The aim of this proposal is the detection of oscillations of
periods of approximately 3 to 5 mn in different layers of the solar
atmosphere, from the photospheric level to the high chromosphere.
We want to detect these oscillations and eventually compare their frequency
in both magnetic and non magnetic regions of the chromospheric network,
and to study the temporal behaviour of the oscillations at different
heights in the solar atmosphere using simultaneous observations
in different lines. These waves could partly explain heating of the corona
(in loops for example) and acceleration of the solar wind thanks to the
coupling with Alfven waves.
Several recent works brought evidences of 3mn and 5mn waves detection
at several level in the solar atmosphere: Bocchialini & Baudin (1995)
found waves both in and out of the chromospheric network and showed
their propagation using wavelet transform; Curdt & Heinzel (1998) observed
oscillations in the Lyman lines using SUMER data; Gouttebroze et al.
(1999) found oscillations in the intensity variation of lines formed in the
upper chromosphere; Gallagher et al. (1999) found evidences of waves higher,
at the level of the transition region.
Our aim for this JOP is to follow the propagation of wavetrains by the
application of wavelet analysis to simultaneous time series, from the
photospheric level (MDI observations) up to the transition region (with
CDS observations) through the chromosphere (SUMER observations).
B) Proposed observations
------------------------
*SUMER:
1st sequence: (context image)
Area: 30" x 120"
Lines: S IV (1072.99 A), S III (1077.13 A)
Location: disk center
Exposure Time: 15 s
2nd sequence:
Slit selection: 1" x 120"
Lines: S IV (1062.67 A), Si IV (1066.63 A), S IV (1072.99 A), S III (1077.13 A)
(profiles transmitted / 25 pixels)
Location: disk center
Exposure Time: 30 s
Rate: 1 spectrum (in each line) / 1 minute
Duration: 4 hours (at least)
Rotation compensation by steps of 0.38"
3rd sequence: (context image)
Area: 30" x 120"
Lines: S IV (1072.99 A), S III (1077.13 A)
Location: disk center
Exposure Time: 15 s
*CDS:
1st sequence: (context image)
Sequence name: NTBRMDI1
Area: 240" x 240"
Lines: He I (584.33 A), O V (629.73 A)
Location: same as SUMER at the disk center
Exposure Time: 15 s
No. exposures: 60
Total duration: 15mn
2nd sequence:
Sequence name: NTBRMDI2
Slit selection: 4" x 240"
Lines: He I (584.33 A), O V (629.73 A)
Location: same as SUMER at the disk center
Exposure Time: 15 s
No. exposures: 960
Total duration: 4 hours (at least)
Feature tracking ON
3rd sequence: (context image)
Sequence name: NTBRMDI1
Area: 240" x 240"
Lines: He I (584.33 A), O V (629.73 A)
Location: same as SUMER at the disk center
Exposure Time: 15 s
No. exposures: 60
Total duration: 15mn
*MDI:
Dopplergrams (Full-disk or High-Res)
Sampling: 1 minute
References
-------------
Baudin F., Bocchialini K., Koutchmy S., 1996, A&A, 314, L9
Bocchialini K., Baudin F., 1995, A&A, 299, 893
Curdt W., Heinzel P., 1998, ApJL, 503, L95
Gallagher P., Philips K., Harra_murnion L., Baudin F., Keenan F., 1999,
A&A, 348, 251
Gouttebroze P., Vial J-C., Bocchialini K., Lemaire P., Leibacher J., 1999,
Solar Physics, 184, 253
==========================================================================================
"Search of propagating waves over the chromospheric network"
Frederic Baudin(1), K. Bocchialini (2), J-P. Delaboudiniere (2),
P. Gouttebroze (2), S. Koutchmy (3), J. Leibacher (1), J.-C. Vial (2)
(1)NOAO/GONG, P.O. Box 26732, Tucson, AZ 85726-6732, USA, (2) IAS, Bat. 121,
Universite Paris XI 91405 Orsay cedex, France, (3) IAP, 98 bis Bd Arago,
75014 Paris, France
A) Scientific background
---------------------
The latest works performed in the 1083nm He I line (Bocchialini et al.
1994, Baudin et al. 1996) brought evidences of 3mn and 5mn waves
propagation in the chromospheric network. The use of wavelet transform
(Baudin et al. 1996) allows a detailed search of wavetrains and permits
to follow their propagation (Bocchialini & Baudin 1995). Acoustic waves
seem to be at the origin of the propagation of MHD waves. These
could partly explain heating of the corona (in loops for example) and
acceleration of the solar wind thanks to the coupling with Alfven waves.
Evidences also are reported in the litterature in favor of 5 mn
and shorter periods waves seen in the corona.
The aim of this proposal is the detection of oscillations of
periods of approximately 3 to 5 mn in the high layers of the chro-
mosphere, using images performed by EIT in the He II line. We want
to detect these oscillations and eventually compare their frequency
in both magnetic and non magnetic regions of the chromospheric network.
We should be able to measure the rather small modulation (around 1%)
produced over a single pixel by the pressure variations due to the
oscillations, and/or the small displacements due to transverse
waves if the velocity is not far from the sound velocity (beta>1).
It is also not excluded that the phasing of waves propagating in
different magnetic 'flux tubes' gives a large signature in intensity.
It should also be very interesting to derive k-omega diagrams, and
to study the temporal behaviour of the oscillations at different
heights in the solar atmosphere using simultaneous observations
in different lines.
Interpretation of EIT images will be done thanks to the
analysis of SUMER spectra. We remind that the contribution function of
the EIT 304 A He filter includes a large contribution coming from the
coronal emission. It is urgent to calibrate what is the origine of the
intensity fluctuations seen in this filter. Strictly simultaneous
observations are needed, because variabilities are of rather short
periods.
SUMER spectra should simultaneously show a chromospheric
and a coronal lines taken somewhere near the fov of the EIT sub-fields
preferably at the same time with a precision of better than 10 s of
time.
Supporting ground-based observations will be done from Sacramento Peak
Observatory ; images of the same region will be collected in the H alpha
line, Ca II K line, He I D3 line (if weather permits).
B) Proposed observations
------------------------
*EIT:
-Observed line: He II at the wavelength of 304 A.
-Duration of observation: a time sequence of images as long as possible.
A strict minimum of order of 4 hours is necessary, but more would
be much better.
A sampling time of 1mn is required, but a shorter sampling
(30s) would be also much better, allowing spectral analysis at high
frequencies.
-Size of field of view: a subfield of 160 pixels in the EW direction,
96 pixels in the NS direction e.g. 5x3 blocs.
-Dates:
a- Because coordinated observations with ground-based observatories
is planned but not absolutely required, it is desirable to use
a 1st period of observation between the 10th to the 17th of
December, 1996, between 15 and 23 UT (solar visibility at
Sac Peak) .
b- Any periods when the disk center or the equatotial band is free
of activity; a trans- equatorial CH is also a good candidate.
-Location: region at the disk center (and, later, different values
of cos theta) and eventually at the pole.
*SUMER:
Slit selection: 1" x 300"
Lines: Ne VIII (770.4 A / 780.3 A), O IV (787.7 A), N II (775.9 A)
(profiles transmitted / 25 pixels)
Location: disk center
Exposure Time: 30 s
Rate: 1 spectrum (in each line) / 1 minute
Duration: 4 hours (similar to the EIT runs).
*Sacramento Peak Observatory (NSO/SP)
Location : same region
Lines: H alpha line, Ca II K line, He I D3 line
References
-------------
Baudin F., Gabriel A., Gibert D., Palle P.L., Regulo C., 1996, A&A, 311, 1024
Baudin F., Bocchialini K., Koutchmy S., 1996, A&AL, 314, L9
Bocchialini K., Vial J-C., Koutchmy S., 1994, ApJL, 123, L67
Bocchialini K., Baudin F., 1995, A&A, 299, 893